A. Field of the Invention
The present invention relates generally to semiconductor manufacturing and semiconductor devices and, more particularly, to double gate metal-oxide semiconductor field-effect transistors (MOSFET).
B. Description of Related Art
Transistors, such as MOSFETs, are the core building block of the vast majority of semiconductor devices. Some semiconductor devices, such as high performance processors, can include millions of transistors. For these devices, decreasing transistor size, and thus increasing transistor density, has traditionally been a high priority in the semiconductor manufacturing area.
Conventional MOSFETs have difficulty scaling below 50 nm fabrication processing. To develop sub-50 nm MOSFETs, double-gate MOSFETs have been proposed. In several respects, the double-gate MOSFETs offer better characteristics than the conventional bulk silicon MOSFETs. These improvements arise because the double-gate MOSFET has a gate electrode on both sides of the channel, rather than only on one side as in conventional MOSFETs. When there are two gates, the electric field generated by the drain is better screened from the source end of the channel. Also, two gates can control roughly twice as much current as a single gate, resulting in a stronger switching signal.
Transistors on a semiconductor device are often connected into groups that implement higher level logical gates. One frequently used logical gate is the NOR gate. Conventionally, four transistors, such as four double-gate MOSFETs, are used to create a NOR gate.
It would be desirable to more efficiently implement a logical gate such as a NOR gate, as this would increase the overall efficiency of the semiconductor device.